Expansion and seismic joint covers

ABSTRACT

A seismic/expansion joint seal and cover comprising a cover plate, a central spine extending downwardly from the cover plate, and at least one layer of a resilient compressible foam sealant on each side of the spine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of seismic and expansionjoint covers.

2. Description of the Related Art

Expansion and seismic joint covers are, essentially, covers or mechanismdevices to cover expansion and seismic joints to provide pedestrian orvehicular passage over a joint, and provide a smooth transition from oneslab to another, while not inhibiting joint movement or restricting thismovement as a result of the mechanism employed. Generally, themechanisms employed to position the expansion/seismic joint cover overthe joint are either of a mechanical nature or make use of an elasticand recoverable element to provide the impetus (spring-memory orreturn-force) to maintain the joint cover in a median position relativeto the joint movements occurring. These movements may be experienced inal three planes, such as expansion and contraction, deflection and shearof the joint.

Various mechanisms are thus employed to deal with this three directionalmovement and the mechanism to stabilize the expansion joint cover andrestore it into a “neutral position” relative to the movement that hastaken place.

FIG. 1 is a typical prior art expansion/seismic joint cover manufacturedby Migua Fugensysteme GmbH & Co. KG, in Germany particularly for SeismicJoints. As can be seen, this has a cover plate extending across thewidth of the joint to allow for both vehicular and pedestrian traffic.As a self-centering mechanism, it utilizes the recovery ability ofelastomeric extrusions. These extrusions exert the return force requiredto reposition the cover plate as a result of movements occurring in thejoint. The dotted line, seen midway through the joint, is a horizontalbar set across the width of the joint to act as a stabilizing elementfor the elastomeric extrusions in the center. It is there to addstability to the joint and allow the central (metallic) part of thejoint to be fastened to the cover plate, prior to its (the horizontalbar) removal. This expansion/seismic joint cover is intended to bewatertight. The waterproofing is confined substantially to the uppersurfaces of the joint immediately below the cover plate. However, oncethe horizontal (stabilizing) bar is removed, remedial work on the jointis difficult as removal of the cover plate will allow the centralportion of the joint to collapse as it is no longer supported (by thehorizontal bar).

FIG. 2 shows an expansion/seismic joint made by Watson Bowman AcmeCorp., in the U.S.A. In this design, the cover plate is attached to ascissors-type mechanical device immediately below it. The scissors-typemechanism is similar to a “pantograph” or expanding scissors typehot-plate mat. In other words, a scissors-type movement containedbetween nylon bearings and running the length of the joint. In this typeof mechanism, an increase or decreases in the joint width will result inthe repositioning of the cover plate along the center line. However,this expansion/seismic joint cover is not watertight immediately belowthe cover plate—as in the case with the expansion/seismic joint cover inFIG. 1. Thus, an elaborate system of gutters attempts to provide asolution to the watertight issue. The joint, in effect, suffers fromthree major problems. Firstly, an inability to inspect and clean out thejoint other than by removal of the whole joint assembly (the scissorsmechanism prevents direct access into the joint below the cover or slideplate). Secondly, the ingress of waterborne salts into the joint willseriously affect the long term performance of the self-centeringmechanism. Thirdly, the joint design lacks “watertight properties”.

The above prior art illustrated two objects of the present invention.The first is that the cover plate should be removable to permitinspection of the joint below. The second object is that the jointshould be watertight at, or immediately below, the line of waterproofingthat is applied to the deck. This will ensure a waterproofing line ofintegrity across both decks, on either side of the joint, and throughthe actual joint itself.

It can be seen from FIGS. 1 and 2 that the emphasis, until this point intime, has been to utilize either a mechanical mechanism or elastomericextruded profile as the correcting or centering element required tomaintain the cover plate in its correct position relative to jointmovement occurring beneath it. In other words, the cover plate cannot beallowed to merely sit on the surface of the joint but must be guided tomaintain a central position or neutral position relative to the jointmovement occurring.

SUMMARY OF THE INVENTION

In the present invention, then, the present invention relates to aseismic/expansion joint seal and cover comprising a cover plate, acentral spine extending downwardly from said cover plate, and at leastone layer of a resilient compressible foam sealant on each side of saidspine.

In the present invention, the use of an impregnated foam sealant as anelastic recovery or return force mechanism has the dual advantage thatthe system can remain watertight immediately below the level of thecover plate while at the same time the impregnated foam sealant acts asthe return force or stabilizing element for the cover plate.

In an alternative embodiment of the present invention, a waterproofmembrane, eg. a bellow or pre-folded type of membrane is provided belowthe cover plate, spanning the joint and running the entire length of thejoint. In this embodiment, the resilient-impregnated foam may bediscontinuous along the sides of the central spine, whereby elasticrecovery is achieved by means of the resilient impregnated foam layers,by waterproofing is achieved by the membrane above.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a prior art seismic/expansion jointcover made by MIGUA;

FIG. 2 is a cross-sectional view of a prior art seismic/expansion jointcover made by Watson Bowman;

FIG. 3 is a cross-sectional view of a first embodiment of the presentinvention;

FIG. 4 is a cross-sectional view of a second embodiment of the presentinvention;

FIG. 5 is cross-sectional view of a third embodiment of the presentinvention;

FIG. 6 is a cross-sectional view of a fourth embodiment of the presentinvention;

FIG. 7 is a cross-sectional view of a modified form of the embodimentshown in FIG. 5;

FIG. 8 a cross-sectional view of another modified form of the embodimentshown in FIG. 5;

FIG. 9 is a cross-sectional view of a further modified form of theembodiment shown in FIG. 5;

FIG. 10 is a cross-sectional view of a modified form of the embodimentshown in FIG. 6;

FIG. 11 is a cross-sectional view of a modification of the invention,illustrated in connection with the FIG. 4 embodiment, but applicable tothe embodiments shown in FIGS. 4 to 10;

FIG. 12 is an end view of the membrane shown in FIG. 11; and

FIGS. 13 and 14 are end view of clips for installing the membrane ofFIG. 12 in a joint.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplification set out hereinillustrate preferred embodiments of the invention and suchexemplification is not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 illustrates the simplest form 1 of the present invention. Thisessentially consists of a T-piece 2 that acts as both the cover/slideplate and mechanism for self-centering of the cover plate. The leg ofthe T extends into the joint. Its length is dependent on jointdimensions and the size of the pre-compressed expanding foam sealant 3placed on either side of the leg. As can be seen from FIG. 3,impregnated expanding foam sealant such as 20H™ System or GREYFLEX™ fromEmseal Corporation is placed on either side of the leg of the T.

Thus, the system is in equilibrium if the expansion force of theimpregnated expanding foam sealant to the left of the T is equal orequivalent to that being exerted by the impregnated expanding foamsealant to the right of the T. The system, such as, can be considered“at rest”. Should the joint experience an extension due to a decrease intemperature or as a result of other movements, the impregnated expandingfoam sealant will have to fill a greater void or distance between thefaces of the joint. Due to its expanding nature, it will do so inrelation to the movement experienced and thus come to a new “rest”position. In this new rest position, forces to the left of the T willbalance those to the right of the T thus enabling the cover plate/slideplate to remain centered over the joint.

However, the FIG. 3 configuration does not allow for an inspection ofthe joint beneath the slide plate as the T section is one solid piece.Therefore, provision must be made, as in FIG. 4 onwards, for the abilityto remove the top cover plate/slide assembly from that portion containedwithin the throat of the joint. This is achieved as shown in FIG. 4. Inaddition, the section contained in the joint may be provided with upperand lower base flanges 5 (as shown) to position the impregnatedexpanding foam sealant 3 more accurately and, in addition, enable thevertical element 2 to be secured to the cover plate/slide plate 4.

FIG. 5 is an alternate embodiment that allows for the removal of thecover plate/slide plate. This design allows for the fact thatirregularities in joint construction may exist in regard to both thehorizontal and vertical joint sizing parameters. In other words, jointsides may not be perfectly parallel to one another or equidistant fromone another. The joint design criteria may not be met during actualfield construction of the joint. In this case, the expansion of theimpregnated expanding foam sealant on the left side of the T piece maynot be perfectly matched with the expansion characteristics of theimpregnated expanding foam sealant on the right hand side of the Tpiece. This will be due to joint irregularity, in width, vertical, andhorizontal alignment, occurring during the construction process. Thissituation should be corrected to allow the cover plate/slide plate toremain (slide) in contact with both opposing slabs that form the uppersurface of the joint. The configuration of FIG. 5 will allow, bytightening of the respective screws 6, the ability to pull down theslide/cover plate to the degree that is necessary and so enable it torest on one or other side of the joint in the correct manner.

The embodiment of FIG. 6 is an adaptation of that shown in FIG. 5.However, in this case, the means to adjust the final position of thecover plate/slide plate is moved to immediately below the cover/slideplate.

It will be observed that the upper base flange in the embodiment of FIG.6 is incorporated in an angulated portion 7 that is adjustable relativeto the central spine 8 by means of vertically extending slots in thespine and/or the angulated portion, through which bolts 9 extend, whichcan be tightened after the angulated portion is at the correct height.It will be appreciated that in selecting the material from which theangulated portion is to be fabricated, consideration should be given toflexibility, since a joint may be somewhat uneven along its length. Foam3 is not shown in FIG. 6 for clarity of illustrating the other elements.

Referring now to FIG. 7, modifications to enhance the water resistanceof the joint directly beneath the cover plate are illustrated. Thewatertight properties of an impregnated expanding foam sealant both tothe left and right of the T piece may be enhanced by the creation of adouble seal at the upper surface level of the impregnated expanding foamsealant closest to the cover/slide plate. This may be achieved thoroughthe use of a low modulus or ultra low modulus sealant 10 being appliedto this surface layer. The use of an ultra low modulus sealant (such asDow Corning 890 RTV Silicone Sealant) will provide the surface of theimpregnated expanding foam sealant 3 with a closed cell finish andadditional sealant layer which will reduce the depth requirement of theimpregnated expanding foam sealant beneath the low modulus sealant. Inaddition, the use of the correctly chosen wet sealant adhered to boththe central spine and joint substrate will enhance the elasticproperties of the double seal configuration. In the FIG. 7configuration, the impregnated expanding foam sealant 3 will act as theprimary return force or memory, while the ultra low modulus sealant willact as the primary watertight barrier, while also enhancing the returnforce or memory of the composite seal. It can be seen from thisconfiguration that if this ultra low modulus sealant is applied in aself-leveling format, after the impregnated expanding foam sealant hasbeen placed in the joint and allowed to recover to joint size, that awatertight element is obtained in terms of adhesion to the substrates.

The FIG. 7 installation is effected firstly by the installation of the Tpiece with impregnated expanding foam sealant applied to both sides ofthe T piece or central spine. This assembly is adhered to the jointfaces by means of a suitable adhesive and allowed to recover from itspre-compressed delivery and installation format. After recovery of thepre-compressed impregnated expanding foam sealant, the ultra low modulusself-leveling sealant (or other suitable sealant) is applied to the topexposed surface of the impregnated expanding foam sealant on either sideof the central spine. Once the sealant has been applied, a level may beapplied across the top surface of the joint to correctly align thebrackets and cover plate/slide plate. The cover/slide plate 4 is thenscrewed into position.

FIG. 8 shows a further modification and makes use of a prepackagedproduct 11 consisting of layers of compressible and non-compressiblefam, with a sealant applied to the top surface thereof, sold under thetrade-mark COLORSEAL™, by Emseal Corporation. In the case of the use ofthe Colorseal™ product, a finishing of the detail will require that acorner or “heel” bead be applied to effect the proper chemicaltermination and adhesion of the top sealant to the substrate.

It can be seen from FIGS. 7 and 8 that the system can be extended toutilized interleaving layers of impregnated expanding foam sealant andclosed cell foam or other resilient material to assist in the recoveryand stability of the composite structure that is placed on either sideof the central spine. In other words, a composite matrix may be utilizedas the return or recovery force on either side of the central spine. Theprime requirement is that the material to be inserted into the joint iscapable of being pre-compressed and holding this pre-compression duringthe time taken to install the material correctly into the joint. So, aseries of both differing densities of impregnated expanding foam sealantand closed cell foam may be used to provide the recovery force. Thisrecovery force and composition of the structure will, to a large extent,depend on the size (width) of joint to be formed together with theperformance characteristics required from the joint (such as seismic orthermal movement characteristics, etc.).

It will be observed from FIGS. 9 and 10 that further combinations arepossible. FIG. 9 illustrates a form of the present invention utilizing asplit central T-piece similar to that shown in FIGS. 5 and 7, with alayered compressible and non-compressible foam layers, available fromEmseal Corporation under the trade-mark BACKERSEAL™ 12 applied on eachside of the T-piece, and a low modulus wet sealant applied in the fieldon the top surface of same, after it has expanded on each side to centerthe T-piece.

FIG. 10 illustrates a modification of the FIG. 6 form of the invention,described in full above, but utilizing COLORSEAL™ product 11 as acentering means on each side of the T.

The cover/slide plate construction may be chosen from the metallic groupof materials including stainless steel, bronze, brass, aluminum,galvanized or plated steel, etc. The main criterion for the choice ofmaterial is that allowable degree of flexing that is undergone duringthe passage of vehicular or pedestrian traffic while the material stillretains its ability to bridge the joint in the manner required by thedesign engineer. In addition, the material should displaycorrosion-resistant properties if used in an external environment. Thus,the larger the joint that must be spanned by the cover/slide plate, themore rigid the material. Conversely, as the gap to be spanned becomesnarrower, the distance between the joint faces is less and alternatematerials may be used, such as thermo-plastics or thermo-plastics alloys(elastomers). The main criteria for the use of such alloys are impactresistance, rigidity in load transfer, and temperature resistance ifexposed to an external environment. It can thus also be seen that thecover/slide plate may be constructed from composite materials such asfiber resins.

Thus, the final choice of material will depend on joint width, loadtransfer, and structural integrity of the joint assembly.

The sub-assembly beneath cover/slide plate may be chosen from the groupof metals including steel, aluminum, brass, and bronze, which may beextruded or rolled to form the necessary sections. The material shoulddisplay corrosive-resistance properties in accordance with theenvironment in which it will operate (interior/exterior). However, thechoice of material may also include rigid plastics, thermo-plasticalloys, and co-extrusions that are able to be fastened to thecover/slide plate and provide the cover/slide plate with sufficientretention and movement capability in relation to the movements beingexperienced by the joint.

The preferable choice of material would be aluminum extrusions.

Reference now is made to FIGS. 11 to 14, where an alternative to usingcontinuous length of resilient foam sealant on each side of the centralspine is illustrated.

It has been found that the equilibrium force necessary to achieveequilibrium and thus create an “at rest” system, is in fact smaller thanthe total force actually exerted by a continuous run of impregnatedexpanding foam sealant (or the composite interleaved structure) to theleft and to the right of the spine. In other words, the equilibrium ofthe system, and an “at rest” position, may be achieved by adiscontinuity of impregnated expanding foam sealant (or the compositeinterleaved structure) to the left and to the right of the spine. Assuch, the amount of impregnated expanding foam sealant (or the compositeinterleaved structure) may be reduced by as much as two-thirds, thusproducing a substantial cost-saving. The modification is that theapplication of, for example, 250 mm long sections of impregnatedexpanding foam sealant (or the composite interleaved structure) placedopposite one another on either side of the spine may be followed by afurther section containing no material (void). This takes place in thelength of the joint. So, a section filled with impregnated expandingfoam sealant (or the composite interleaved structure) may be followed bya section with no material at all. The distance between sections willdepend on the size of the joint, its vertical or horizontal status, andwhether it is being subjected to vehicular, pedestrian, or othertraffic. Ideally, the void section would not be greater than twice the“sealed section”. “Sealed” sections will be about 0.3 to about 2.0meters long.

However, it can be seen from the above that as a void section has nowbeen created on either side of the T and along the line of sealant, thatthe second objective, “that the joint should be watertight at, orimmediately below, the line of waterproofing that is applied to thedeck”, is not met.

In order to reinstate this objective, a “sealant line” is achievedthrough a flexible waterproof membrane 13 attached to either side of thejoint face and placed immediately below the cover plate assembly, asshown in FIG. 11.

The waterproof membrane 13 may be manufactured from flexible plastic,rubber or neoprene, or thermo-plastic alloys (elastomers). Thewaterproof membrane may be either in sheet form, looped sufficiently inthe joint to allow correct seismic or other movement, or may be in theform of an extrusion or molding. The example shown in FIGS. 11 and 12 isof an extrusion with bellows-sections, allowing for the expectedmovements of the joint for which it is intended. The thickness ofmaterial is variable, as the membrane is subject to support, atintervals, by the staggered sealant below. Thus, the thickness isultimately determined by the head of water that the entire system isexpected to sustain. The lower the head of water, the thinner themembrane may be. Ideally, for an extruded section in a continuouslength, the thickness of material may be in the order of 1-5 mm. Therange in thickness only being subject to the conditions alreadydescribed above and the ease of handling of the extruded section on siteand during installation.

Two fixing methods or attachment methods, for attaching the membrane tothe substrate, are shown. However, the essence of the modification isthat the membrane would extend from one vertical side of the joint tothe other vertical side. Numerous attachment methods are available asessentially the membrane will not be exerting a tear strength along itsline of attachment. The movement of the membrane will be guided andassisted by the movement of the T piece.

In FIG. 13, a clip 14 that attaches to a shallow squared notch in thejoint is shown (as further shown in FIG. 11). The clip accepts the edgesof the membrane 13, which may have barbs or other thickenings formed inthem for a tight fit. Additionally, an adhesive bead may be applied intoclip 14 before the edge of the membrane is inserted. Clip 14 may be anextrusion of aluminum, or a high density plastic, and may be grouted oradhesively attached to the joint in a waterproof manner, along thelength of the joint, on both sides.

As shown in FIG. 14, a clip 15 may be provided that attaches to theinside wall of the joint. This clip may be attached to the joint wall bya fastener 15 such as a nail or screw, but should also be sealed alongthe joint. Such a clip will also accept the edge of the membrane, and isalso a plastic or metal extrusion that extends the length of the joint,along both sides thereof.

It is to be understood that the examples described above are not meantto limit the scope of the present invention, it is expected that thenumerous variants will be obvious to one skilled in the field of jointseal design without any departure from the spirit of the invention. Theintended claims, properly construed, form the only limitation on thescope of the invention.

1. A seismic/expansion joint seal and cover comprising: a cover plate; acentral spine extending downwardly from said cover plate; and at leastone layer of a resilient compressible foam sealant on each side of saidspine.
 2. A joint and cover as claimed in claim 1, wherein said cover isdetachable from said spine.
 3. A joint seal and cover a claimed in claim2, wherein said cover is screwed to said spine.
 4. A joint seal andcover as claimed in claim 3, wherein said spine is composed of twomirror-image generally C-shaped members, each of which has a lower baseflange, an upper base flange into which said cover is screwed, and aflat web extending between the flanges, against which said foam sealantis positioned.
 5. A joint seal and cover as claimed in claim 4, whereinsaid C-shaped members are separated by a strip of incompressible foam.6. A joint seal and cover as claimed in claim 2, wherein a bead ofsealant is applied between said spine and said cover.
 7. A joint sealand cover as claimed in claim 3, wherein a bead of sealant is appliedbetween said spine and said cover.
 8. A joint seal and cover as claimedin claim 4, wherein a bead of sealant is applied between said spine andsaid cover.
 9. A joint seal and cover as claimed in claim 5, wherein abead of sealant is applied between said spine and said cover.
 10. Ajoint seal and cover as claimed in claim 9, wherein said layer ofresilient compressible foam on each side of said spine is discontinuous,and a waterproof membrane is provided above said spine, beneath saidcover.
 11. A joint seal and cover as claimed in claim 10, includingclips for connecting the edges of said waterproof membrane to the edgesof a joint.
 12. A joint seal and cover as claimed in claim 11, whereinsaid resilient compressible foam sealant is provided in discretesegments on each side of said spine, separated by spaces up to twice thelength of said discrete segments.
 13. A joint seal and cover as claimedin claim 12, wherein said membrane is a folded bellows type membrane.